function nextCardSide()
{
  var cardSides = document.getElementsByClassName('sub_card_details');
  
  for(var a = 0 ; a < cardSides.length ; a++)
  {
    if(cardSides[a].style.display == "block")
    {
      cardSides[a].style.display = "none";
      var nextSide = (a + 1 >= cardSides.length) ? 0 : a + 1;
      cardSides[nextSide].style.display = "block";
      return;
    }
  }
}